Echolocation of the Little Brown Myotis has been well studied since the invention of bat detectors, electronic devices that can "hear" the ultrasonic calls bats make, which are usually beyond the range of human hearing. The Little Brown Myotis typically produces calls lasting about 4 milliseconds. While cruising, they emit echolocation calls about 20 times per second, spacing the pulses at 50 millisecond intervals. When attacking airborne prey, the pulse rates rise drastically, to 200 per second, with only 5 millisecond gaps between calls. The information the bats receive through echolocation allows them to orient themselves, and to locate, track, and evaluate their insect prey. The Little Brown Myotis feeds near or over water, mainly on aquatic insects such as caddis flies, mayflies, and midges, and typically they consume half their body weight in insects each night. Nursing females may eat up to 110 percent of their body weight each night.

Also known as:
Little Brown Bat

Sexual Dimorphism:
Females are slightly larger than males.

Length:
Average:
87 mm
Range:
60-102 mm

Weight:
Average:
10 g
Range:
7-13 g

References:

LeConte, J.E. 1831. In McMurtrie, H., The animal kingdom arranged in conformity with its organization, p.431. (By Baron Cuvier, trans. from French with notes and additions by McMurtrie). Carvill, New York, 1:1-448.